These clay pebbles also known as leca, have a lot of different uses, from a way to raise humidity around house plants, (simply lay them and soak, on a saucer under your favourite pot) to a full on reusable growning medium, or mixing with your preferred substrate as a way of adding drainage around roots to aerate them. You can also try adding them to the bottom of your pot below the soil layer to improve drainage
If you want the water to drain around the roots to aerate them, leave the pellets whole. You can use leca alone or mix them in with the soil. A 30 – 70 (30% percent of leca, and 70% for soil) works great in improving the water-holding capacity of the mixture.